This core will provide the framework for sustained communication among research projects, cores, governmental agencies, and interested parties through monthly seminars, our website, and meetings. A central theme of the proposed RTC activities is more direct involvement with ongoing priorities of selected governmental agencies responsible for minimizing human exposure to arsenic (As) and manganese (Mn) through domestic water supplies derived primarily from groundwater. Each public agency will be encouraged to identify and share relevant data holdings. We will integrate these multi-source data into an accessible Geographic Information System (GIS) and produce maps to enhance monitoring and regulatory decision making. The data integration will assist agencies and other stakeholders lacking GIS capacity and permit others to expand their capabilities. The public agencies involved are located in four states (NJ, NY, NH, ME) and include county as well as federal and state personnel. Our approach will be to integrate existing geophysical, geochemical, hydrological, and socio-demographic data for the Newark basin and adjacent areas of northern NJ and southern NY to assess sources (natural and anthropogenic) and human exposure to elevated groundwater As and Mn. These efforts will include field collaboration with government programs in Rockland County and six other counties in the Hudson valley. Environmental isotopes (tritium-3He) will be measured to derive groundwater recharge histories relevant to As and Mn concentrations. Landfills as a potential source for elevated groundwater As and Mn will be evaluated through joint field and laboratory measurements of iron (Fe) floe deposits, indicative of their mobilization in suboxic to anoxic groundwaters. Preliminary measurements of Fe floe chemistry adjacent to landfills indicate frequent high levels of As in areas that include large numbers of new homes using private wells. As part of an investigation of potential impacts of elevated drinking water As on cognitive function in children, two of our research projects will involve numerous measurements of groundwater chemistry in two New England states. We will integrate the new data into GIS formats compatible with those employed by public agencies in NH and ME to help evaluate patterns of exposure to As and Mn in groundwater. Information on exposure potential and treatment options will be shared with the public primarily through governmental agency communication channels.